Matched by chemical composition and mechanical properties, not a formal equivalence claim. Always verify against the applicable standard before substitution.
Chemical Composition (%)
C
Si
Mn
Ni
Cr
S
P
<=0.25
0.10-1.00
<=1.00
1.00-3.00
15.5-20.0
<=0.045
<=0.045
Mechanical Properties
Tensile Strength
≥849 MPa (55 tons/sq in, converted)
Yield Strength
≥680 MPa (44 tons/sq in, converted)
Elongation
≥15%
Hardness
248 HB
Condition
Hardened and tempered (ruling 6), ruling section 6 in (lowest-strength condition of the standard)
More data from BS 970:1955
From the standard
Condition of material on delivery
A
Bars and billets for forging as rolled or forged unless order states otherwise.
B
Forgings and drop-forgings finally heat treated unless order states otherwise.
C
Bars for machining finally heat treated unless order states otherwise.
D
Bright bars finally heat treated, before or after cold work at manufacturer option, unless order states otherwise.
Source: BS 970:1955, Part 2, En 57 (page 168)
Mechanical properties
Condition
Ruling section or size (in)
Tensile strength (tons/sq in)
Yield stress (tons/sq in)
Elongation (%)
Izod impact (ft lb)
Brinell (HB)
Proof stress 0.2% (tons/sq in), when requested
Hardened and tempered (ruling 6)
6
55
44
15
15
248
-
Hardened and tempered (ruling 2 1/2)
2 1/2
55
44
15
25
248
-
-
-
-
-
-
-
41
Values as printed in BS 970:1955; tensile strength, yield stress and proof stress in tons/sq in, Izod in ft lb. Minimum unless a range is shown.
Source: BS 970:1955, Part 2, En 57 (page 169)
Heat treatment
Harden (oil or air)
950/1020 C
Temper
suitable temperature between 550 C and 650 C
Temperatures in degrees C as printed.
Source: BS 970:1955, Part 2, En 57 (page 168)
Notes
Note
When required as plate, sheet and strip order to BS 1449; as wire order to BS 1554 (Rust, acid and heat resisting steel wire) or BS 2056 (for springs) as appropriate.
Source: BS 970:1955, Part 2, En 57
Status in the 1955 edition
Status
Deleted by Amendment 6
Reason
Amendment 6 (Feb 1970): stainless, heat resisting and valve steels moved to BS 970 Part 4:1970
BS 970:1955 was amended up to Amendment 10 (June 1972); steels were moved to the revised Parts 1 to 5 and deleted from this edition.
Source: BS 970:1955, Amendment slips 6 to 10
Active BS 970:1955 EN57 Listings on M-EX (For Sale)